How flat is flat?

[Harbo]

I have just spent the last few days going round in circles trying to lap the sole of my A5.
In the past I have used several methods of flattening tools - waterstones, abrasive papers glued to glass and sometimes silicon carbide grit on glass.
And I was reasonably happy with my plane until I bought a DMT DuoSharp Plus for a price I could not resist. It was the only one on offer and is a course/fine stone combination.
Having blued the sole I gave the plane a few gentle strokes to reveal enormous cavities (or so they appeared!!) where they had not been apparent before. After several hours on the DMT course side I gave up and resorted to a coarser grit gradually working down in stages, in my frustration, to 50g carbide powder!
But it is still not flat when I clean it up on the DMT!!
Now I am assuming the DMT is flat? - but there are still blue areas where they should not be!! I suppose I am talking of very small differences here but they do look bad?
Anybody know of a plane sole milling service?

Rod

 

[dunbarhamlin]

Think Dick gmbh offer one, but don't know of any on these fair shores.

 

[David C]

Plane soles do not need to be flat flat.

What they must not be is concave from front to back or side to side.

Slight convexity of width and length do no harm and the throat area should be in a plane with the toe and heel.

Bumps just behind the throat are very bad news.

What Dick do have, at very reasonable prices, are wonderfully accurate straight eges.

David Charlesworth

 

[David C]

BTW,

DMT stones are not as flat as you might imagine.....

It is easy to "see" this as you change from one grit to another, you will observe a different scratch pattern. Or scratch patterns in different areas.

DMT try hard but precision flatness is a very expensive commodity, unless it comes from china, (granite surface plates).

David

 

[ike]

Having blued the sole

Therein lies part of your problem. Engineers blue as I regard it is very useful stuff when you are very close to flat and are using a hand scraper to take off 'high' spots - e.g a machine slideway etc. Trouble is it isn't much use for anything more than a thou or so out of flatness. It just makes things look much worse than perhaps they are. After all a thou and a half tol on a a plane sole will not compromise its function (IMO but I would respect DC's professional judgement on that point).

cheers,

Ike

 

[engineer one]

rod, i too found problems when sharpening the backs(fronts) of various tools with a dmt, so i would look for a different indicator.

in metal working terms this is an even and similar set of scratch marks across the sole of the plane or any other surface. as inventor says, engineers blue is really only for very fine finishing.

what is much more telling is that you have a constant looking surface with the pattern seeming to be common across the sole.

when you move from one grade of grit to another if it is flat and level, then the finer grit will within a short period remove all those marks which are more coarse.

the other problem to consider, is that you have to try and hold the plane at right angles to the grinding surface. sometimes made more difficult by using a dmt type of stone.

go back to sand paper/ wet and dry on glass i think

good luck rod

paul :wink:

 

[Wiley Horne]

Hi Harbo,

Two thoughts.....Thought 1, don't get it flat. Get it self-jigging to plane flat, with the periphery, heel, toe, and leading edge of mouth in the same plane. Slightly hollow elsewhere is fine; it's your guarantee you haven't convexed the sole by lapping.

Thought 2...David mentioned a Chinese granite surface plate. If you obtain one, this will be some of the best money you will ever spend in woodworking (IMO/IME).

Congratulations on the A5. Wonderful planes.

Wiley

 

[Joel Moskowitz]

I have taught several seminars on plane flattening and flattened my own A5 (and many other planes) about 20 years ago. I used to scrape the plane to a surface plate. A reliable but slow method. The problem with sandpaper on a flat surface is the danger or rocking the plane through the stroke.

Recently - a few years ago anyway - I started using another method which is far far simpler and considerable faster. What I do now is check the plane with a straightedge. left right, front back, diagonal etc. you can use a store bought straightedge or make one out of wood using a matched pair for accuracy - in any case once I determine the high spots I attach them locally with a bit of sandpaper. I don't work the whole surface just the high spots. checking my progress because in fact very little material needs to be removed. it's faster, very reliable and it avoids over flattening and introducing errors. One point - on isolated areas the sandpaper can be used in the hand but for anything near the mouth you want to use a small hard sanding block so that you don't round over the areas near the mouth.

 

[Frank D.]

Thanks for the tip Joel, makes a lot of sense!

 

[Paul Chapman]

I agree with those who say you don't have to get the whole of the sole flat - to do that will take you forever. Concentrate on the toe, heel and around the mouth. I've done a few old planes recently and really transformed their performance. They still have a few hollows but in places where it doesn't matter. They now produce consistent, gossamer-thin shavings

Cheers :wink:

Paul

 

[Anonymous]

The main thing is; did your plane work effectively or not? If not, then was a non-flat surface definitely the reason?
IMHO a lot of people spend a lot of time pointlessly going down this route, infact I've never flattened a plane sole in my life.
I might have go one day - I've got a 4 1/2 Stanley which I've never been able to get to work very well, but all my other rubbishy planes have been no prob.

cheers
Jacob
PS Come to think - I flattened a wooden jack plane and once rubbed up a little Stanley 102 block plane on emery paper for a few seconds. Both improved performances.

 

[David C]

It takes me about two minutes to demonstrate that a plane with a hollow in its length will not plane a straight edge with a fine shaving,

or that a plane with bump behind throat will not take a fine shaving at all.

Jacob must either have been very lucky with his planes or have different criteria from those of fine cabintmakers working in difficult hardwoods.

The vast majority of old Stanley and Record planes which show up in my workshop are immesurably improved by some tuning and flattening.

David Charlesworth

 

[Paul Chapman]

I've never flattened a plane sole in my life.
I might have go one day - I've got a 4 1/2 Stanley which I've never been able to get to work very well, but all my other rubbishy planes have been no prob.

In my experience, Jacob, old planes very a lot. I bought a second-hand Record #05 Stay-Set (1960s probably) which has worked beautifully with no flattening at all. My Record #04, Stanley #60 1/2 and Record #778 (which is a very weak design in terms of flatness, both of the sole and the side) which I bought in the 1970s were out quite a bit. Now that I've flattened them they really sing

Cheers :wink:

Paul

 

[woodbloke]

Paul Chapman wrote -

I bought a second-hand Record #05 Stay-Set (1960s probably)

Paul - that's not the one with LCC on the side is it :wink: - Rob

 

[Paul Chapman]

Paul Chapman wrote -

I bought a second-hand Record #05 Stay-Set (1960s probably)

Paul - that's not the one with LCC on the side is it :wink: - Rob

Might be :lol:

Cheers :wink:

Paul

 

[bugbear]

Having blued the sole

Therein lies part of your problem. Engineers blue as I regard it is very useful stuff when you are very close to flat and are using a hand scraper to take off 'high' spots - e.g a machine slideway etc.

I strongly suspect that when Harbo speaks of blueing the sole, he means he scribbled on it with a blue permanent marker.

(similar to "marking blue", as opposed to "engineer's blue")

http://en.wikipedia.org/wiki/Engineer%27s_blue
http://en.wikipedia.org/wiki/Marking_blue

BugBear (who may add to a thread on plane sole flattening later)

 

[Harbo]

Thanks for all the advice folks.

I am not trying to get the sole perfectly flat everywhere - just the important areas around the throat etc.
The results so far are showing a high ridge running down the centre across the throat. There are "hollows" at each side of the throat - one side is worse than the other. The extreme end of the heel is slightly "rounded" but I do not think I can cure that (and is probably not that important?).
The other problem I have is that my so called "straight edges" are giving different results - so perhaps an order to Dick's?
This all started when I had a new iron fitted by Ray Iles who commented that the sole needed lapping - with hindsight I should have probably asked him to do it?
I see that Axminster do a "small granite surface plate" so will investigate that further and yes Bugbear is correct - I am using a blue perm. marker
I seem to be in a "Groundhog" phase at the moment - my so called 6000 grit waterstone put "scratches" on one of my irons when trying to do a final polish - I think I will do a bit of gardening instead for a few days :lol:

Rod

 

[bugbear]

The other problem I have is that my so called "straight edges" are giving different results - so perhaps an order to Dick's?

Given the high price of straight edges, and the small extra cost of surface plates (from APTC, Rutlands or eBay)

http://cgi.ebay.co.uk/Granite-Surface-P ... dZViewItem

I'd prefer a surface plate.

The difficulties of making a flat SURFACE using straight edges is well known to woodworkers, which is why we need winding sticks as well as rulers.

And of course, one can use a surface plate as a reference to calibrate a straight edge (I have done this to my s/h combination square rulers...)

A 12x9 surface plate has a very useful 15" diagonal

BugBear

 

[newt]

I have all the DMT diamond grades except the extra coarse. As David C says they all give a different scratch pattern, my nearly new blue (coarse) is quite concave across its width, next to useless, I guess the plastic base distorts. I could live with it being concave over it length. The solid steel DMT stones are much flatter.

 

[Harbo]

Late this afternoon I was dragged from my gardening to receive a parcel from Woodcraft - I had only ordered it at the weekend - a DMT Extra course/course for $79 plus $30 postage. A saving of nearly 50% over UK prices. ( And no duties)
Anyway I put the extra course side to immediate use and within 30 mins or so the plane sole was acceptably flat!! :lol:

Dick's Plane Truing Service costs between 45Euros to 145Euros depending on the amount of work required. A specially trained craftsman manually scrapes away the raised portions of the sole using a scraping tool - sounds like hard work - so the 45Euros sounds cheap? You do have to allow 3 months for the work to be done though!!

Rod :lol: